socket.io is a great library, agreed. However, a nice thing about standards is you can program to the specification and provide support on other platforms. Working on a project that involves node, a browser client, and a couple of mobile platforms -- socket.io is great for the server->browser websocket or comet case, but for the mobile case investigating the proper library (or hand rolling a compatible WS/comet implementation) is needed.

The step towards standardization will make this type of cross "platform" compatibility easier in the long run.